Download 4 Properties of Matter Chapter Outline Properties of Substances

Slide 1 ___________________________________ 4 Properties of Matter
___________________________________ ___________________________________ ___________________________________ ___________________________________ A burning log undergoes a chemical change resulting in
the release of energy in the form of heat and light
___________________________________ Foundations of College Chemistry, 14th Ed.
Morris Hein and Susan Arena
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ Chapter Outline
2 4.1
Properties of Substances
4.2
Physical and Chemical Changes
4.3
Learning to Solve Problems
4.4
Energy
4.5
Heat: Quantitative Measurement
___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ A. Energy in Chemical Changes
B. Conservation of Energy
4.6
___________________________________ Energy in the Real World
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ ___________________________________ Properties of Substances
3 ___________________________________ Each substance has a set of properties that are
characteristic and give it a unique identity.
Properties are classified as either physical or chemical.
___________________________________ Physical properties are inherent characteristics that can
be determined without altering the composition.
___________________________________ Examples include:
color
taste
odor
state of matter
___________________________________ density
melting point
boiling point
© 2014 John Wiley & Sons, Inc. All rights reserved.
___________________________________ ___________________________________ Slide 4 ___________________________________ Properties of Substances
Chemical properties describe the ability of a substance
to either undergo a reaction with another substance
or to decompose.
Consider chlorine (Cl2).
Physical Properties: 4 times heavier than air, a gas at
room temperature, greenish-yellow in color, bad odor.
Chemical Change:
2 Na (s) + Cl2 (g)
___________________________________ ___________________________________ ___________________________________ 2 NaCl (s)
___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ ___________________________________ Properties of Substances
5 ___________________________________ No two substances have identical
physical and chemical properties!
___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 6 ___________________________________ ___________________________________ Physical and Chemical Changes
___________________________________ Physical changes are changes in physical properties
(such as size and density) or changes in states of matter
without a change in composition.
___________________________________ No new substances are formed during a physical change!
Sawing wood is a physical change – the wood changes
shape, but the resulting pieces are still wood!
___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
___________________________________ Slide ___________________________________ Physical and Chemical Changes
7 In a chemical change, new substances are formed
that have different properties and composition
from the original material.
___________________________________ ___________________________________ When copper metal (Cu) is heated in air, the shiny metal
turns black as copper(II) oxide is formed on the surface.
2 Cu (s) + O2 (g)

___________________________________ 2 CuO (s)
 represents heat
___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ ___________________________________ Common Physical and Chemical Changes
8 ___________________________________ Be able to distinguish between a physical
and chemical change.
___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ Let’s Practice!
9 a.
b.
c.
d.
e.
___________________________________ Which of the following is a physical change?
grinding a rock into powder
hydrogen and oxygen reacting to form water
a shovel rusting
an acid and base reacting to form water
burning sugar
___________________________________ ___________________________________ ___________________________________ Which of the following is a chemical change?
a.
b.
c.
d.
e.
melting aspirin
breaking a plate
boiling antifreeze
putting sugar in tea
lighting a match
© 2014 John Wiley & Sons, Inc. All rights reserved.
___________________________________ ___________________________________ ___________________________________ Slide 10 ___________________________________ Chemical Equations
A chemical equation is used to represent chemical change.
___________________________________ For example, water decomposes into its elements
when electrolyzed.
___________________________________ 2 H2O (l)
2 H2 (g) + O2 (g)
___________________________________ Understanding a chemical equation:
reactants
the starting substances (in this case 2 H2O)
products
the substances formed (in this case 2 H2 + O2)
___________________________________ means “produces”; points towards products
___________________________________ A physical change usually accompanies a chemical change.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ Learning to Solve Problems
11 ___________________________________ To succeed in chemistry, you must learn to solve
complicated problems.
READ
Read the problem carefully and determine
what is known and desired. Use units!
___________________________________ PLAN
Determine the unit relationships needed to
solve the problem. Set up the problem so
that the units cancel correctly.
___________________________________ ___________________________________ CALCULATE Do the math. Make sure the answer contains
the proper units and significant figures.
CHECK
___________________________________ Check the answer — is it reasonable?
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ ___________________________________ ___________________________________ Energy
12 ___________________________________ Energy is the capacity of matter to do work.
There are many types of energy including mechanical,
chemical, electrical and nuclear energy.
___________________________________ Potential energy (PE) is stored energy, the energy
an object possesses due to its position.
___________________________________ A ball located 20 feet above the ground has more PE
than when it is located 10 feet above the ground.
___________________________________ A diver poised on a diving board has a large amount of PE.
When the diver leaves the board, the energy is converted.
___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
___________________________________ Slide 13 ___________________________________ Energy
Kinetic energy (KE) is energy that matter possesses
due to its motion.
___________________________________ When water held by a dam is released, its PE converts to
KE which can be used to produce electricity.
___________________________________ ___________________________________ ___________________________________ Energy can be converted from one form to another.
In chemistry, energy is most frequently released as heat.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ ___________________________________ Heat: Quantitative Measurement
14 ___________________________________ The SI unit for energy is the joule (J).
The energy required to change the temperature of 1 g
of water by 1 °C is 4.184 J.
___________________________________ 4.184 J = 1 calorie
Nutritional calories are actually kilocalories (kcal) and
are represented with a capital C.
___________________________________ Heat and temperature are different concepts.
Imagine two beakers containing water.
In each, the temperature is raised by 30 °C.
The beaker containing twice the water requires twice
the heat to reach the same temperature.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ ___________________________________ 15 ___________________________________ Methane (CH4) is the major compound in natural gas.
Using the reaction below, determine the amount of
energy produced during combustion (in calories).
Knowns
___________________________________ CO2 (g) + 2 H2O (g) + 802.5 kJ
___________________________________ 4.184 J = 1 cal
1000 J = 1 kJ
___________________________________ Solving for calories
Calculate
___________________________________ ___________________________________ Let’s Practice!
CH4 (g) + 2 O2 (g)
___________________________________ 1000 J x 1 cal
802.5 kJ x
= 1.918 x 105 cal
4.184 J
1 kJ
© 2014 John Wiley & Sons, Inc. All rights reserved.
___________________________________ ___________________________________ Slide 16 ___________________________________ Heat: Quantitative Measurement
Every substance has a characteristic heat capacity.
___________________________________ The specific heat of a substance is the amount of heat
(gained or lost) required to change the temperature
of 1 g of the material by 1 °C.
___________________________________ The specific heat of water is much higher
than most substances.
___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ ___________________________________ Specific Heat Capacity
17 When an object is heated or cooled, the amount of energy
transferred depends on three things:
1. The amount of material
2. The magnitude of the temperature change
3. The identity of the material gaining or losing energy
___________________________________ The following equation can be used to calculate heat:
___________________________________ ___________________________________ q = mCT
q is heat
___________________________________ m is mass
C is specific heat capacity
___________________________________ T is change in temperature
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ ___________________________________ Specific Heat Capacity
18 ___________________________________ How much heat is needed to raise the temperature
of 200. g of water by 10.0 °C?
___________________________________ q = mCT
Knowns
___________________________________ m = 200. g
C = 4.184 J/g°C
T = 10.0 °C
Solving For q
___________________________________ q = mCT
Calculate q = (200. g)(4.184 J/g°C)(10.0 °C) = 8.37 x 103 J
© 2014 John Wiley & Sons, Inc. All rights reserved.
___________________________________ ___________________________________ Slide 19 ___________________________________ Specific Heat Capacity
___________________________________ Calculate the specific heat (J/g°C) of an unknown if
1638 J raises the temperature of 125 g
from 25.0 °C to 52.6 °C.
___________________________________ q = mCT
Knowns
___________________________________ q = 1638 J
m = 125 g
T = 52.6 °C – 25.0 °C = 27.6 °C
q
Solving For C C =
mT
Calculate C =
1638 J
= 0.475 J/g°C
(125 g)(27.6 °C)
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 20 ___________________________________ ___________________________________ ___________________________________ ___________________________________ Energy in Chemical Changes
All chemical reactions either absorb or release energy.
Chemical changes can produce different kinds of energy,
like electrical energy in a lead storage battery or
heat and light when fuel undergoes combustion.
___________________________________ ___________________________________ Chemical changes can also use energy,
such as the electricity used to decompose water or
the solar energy used by plants during photosynthesis.
___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 21 ___________________________________ ___________________________________ Conservation of Energy
Energy can be changed from one form to another
or from one substance to another.
___________________________________ The Law of Conservation of Energy states that energy
can be neither created nor destroyed.
___________________________________ When water decomposes, energy is absorbed by the
system so H2 and O2 have higher potential energy.
___________________________________ When hydrogen (H2) is used as a fuel, energy is released
and water (the product) has lower potential energy.
___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
___________________________________ Slide 22 ___________________________________ Energy in the Real World
Energy comes from many sources, including petroleum,
coal and woody plants, all derived from the sun.
___________________________________ We use petroleum deposits in the forms of
gasoline and natural gas.
___________________________________ Petroleum is composed of hydrocarbons, compounds
containing only carbon and hydrogen in differing ratios.
___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 23 ___________________________________ ___________________________________ Energy in the Real World
Natural gas consists mainly of methane (CH4) with
small amounts of ethane, propane and butane mixed in.
___________________________________ Coal is formed from plant remains stored under high
pressure for many years. The higher the carbon content,
the more energy available in the coal.
___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ ___________________________________ The Energy Crisis
24 To keep up with increasing energy demands,
new renewable energy sources are necessary.
___________________________________ Potential resources include solar, nuclear, biomass,
wind and synthetic fuels.
___________________________________ ___________________________________ solar
___________________________________ wind
biomass
© 2014 John Wiley & Sons, Inc. All rights reserved.
___________________________________ ___________________________________